In the wheel suspension of modern motor vehicles different types of springs are used to connect the main (sprung) vehicle structure to the wheels of the vehicle. In addition to spiral springs, leaf springs are also used, amongst others, most commonly in the case of rigid axles. Such a leaf spring extends along the longitudinal axis of the vehicle and generally has a concave-upward shape, for example in the manner of a parabola. In addition to leaf springs made of spring steel, leaf springs made of composite material, for example fiber-reinforced plastics, are sometimes also used. Individual springs or even spring assemblies consisting of two or more springs may be used. The at least one spring is normally connected in a central region via a clamping device, for example by spring clips, to the axle to be sprung.
Such clamping devices complicate the structure of the suspension, whereby the assembly and maintenance become more complex and expensive. Moreover, the use of clamping devices contributes to an increase in the mass and/or the weight, since generally relatively heavy metal parts have to be used to this end. In this case, care also has to be taken that the clamping device is part of the unsprung mass, which should be kept as low as possible. Moreover, the static clamping forces in the case of leaf springs made of composite material may lead to damage and/or to creep.
EP 3 006 237 A1 discloses a leaf spring for a wheel suspension which has an elongated spring body made of composite material. A central region of the spring body has a recess, for example a slot. In the assembled state, a cover part with a projection engages in the recess. Optionally, a further intermediate part made of rubber may be arranged between the cover part and the leaf spring. The leaf spring is clamped via the cover part, for example by means of spring clips, to an axle.
EP 0 162 189 A1 discloses a suspension in which a leaf spring is clamped onto an axle. In this case, it is provided that the leaf spring has a row of transverse ribs on a side facing the axle, said ribs corresponding to transverse grooves configured on the axle. By the cooperation of the transverse grooves and the transverse ribs, a positive connection is produced. Optionally the transverse grooves may be configured on a separately produced intermediate plate which engages by means of a bolt with the axle.
U.S. Pat. No. 4,643,406 A discloses a suspension with a leaf spring which is produced from fiber-composite material and which is clamped onto an axle. In this case, the leaf spring in a connecting region has steel plates which are adhesively bonded, on the one hand, to the leaf spring and, on the other hand, to rubber cushions. The rubber cushions engage in turn in recesses of metal shoes which are arranged on the upper face and lower face of the leaf spring. A lower metal shoe is connected to the axle whilst an upper metal shoe is clamped thereagainst by spring clips.
A clamping device for a leaf spring is disclosed in U.S. Pat. No. 4,801,129 A, in which a plate-like first clamping element is fastened, for example, by welding to an axle. The leaf spring is positioned against this first clamping element by the interposition of a first rubber element. A second rubber element and a second clamping element adjoin the upper face of the leaf spring, said second clamping element arching over the leaf spring and the rubber elements and positively engaging in the first clamping element. By means of a profile which changes in the longitudinal direction of the leaf spring, a positive connection is provided between the leaf spring and the rubber elements and between the rubber elements and the second clamping element. U.S. Pat. Nos. 4,684,110 A and 4,630,804 A disclose a similar structure.
U.S. Pat. No. 6,991,223 B2 discloses a suspension in which a leaf spring made of composite material is clamped between two clamping elements, which in turn produce the connection with an axle. In this case, the clamping elements are arranged in a region of the leaf spring, tapering toward one end within the horizontal plane and widening within the vertical plane. As a result, a type of wedge effect is produced, said wedge effect preventing a longitudinal displacement of the leaf spring relative to the axle via a positive connection.
U.S. Pat. No. 9,470,980 B2 discloses a leaf spring arrangement for a motor axle. This arrangement has a leaf spring, in particular a transverse leaf spring, which has at its ends receivers for attaching to other axle components. The receivers may consist of metal, for example, and are adhesively bonded to the leaf spring. In this case, a positive connection is present between the corresponding joining surface of the leaf spring and the receiver.
With regard to the prior art disclosed, the attachment of an axle to a leaf spring provides further room for improvement. This relates, in particular, to the mass and/or the weight, the complexity of the structure and the avoidance of damage to the leaf spring.